Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 Navigators Insurance Company	Dec. 31, 2013 Lloyd's	Dec. 31, 2012 Lloyd's	Dec. 31, 2013 Lloyd's Syndicate 1221	Dec. 31, 2012 Lloyd's Syndicate 1221	Dec. 31, 2011 Lloyd's Syndicate 1221	Dec. 31, 2013 NMC Operations	Dec. 31, 2012 NMC Operations
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of Navigators Specialty Insurance Company reinsured by Navigators Insurance Company					100.00%
Percentage control of stamp capacity								100.00%	100.00%	100.00%
Property, Plant and Equipment, Useful Life			3 years	7 years
Goodwill and other intangible assets	$ 7,177,000	$ 7,093,000
Goodwill						2,400,000	2,400,000				2,500,000	2,500,000
Other intangible assets						$ 2,300,000	$ 2,200,000